OF ARTS AND SCIENCES : FEBRUARY 10, 1863. . 105 



and they seem to have been so nearly intermediate between the different 

 classes that it may be impossible to fix their place with certainty, 

 either from tracks or skeletons. It is interesting to find that these two 

 sources of evidence illustrate and coiToborate each other. 



9. The question whether the hindmost impression on the outer toe in 

 the fossil footmarks was made by a tarsal bone, or some process on 

 the tarso-metatarsal, has only just engaged my attention. It may have 

 a most important bearing on the whole subject. But I am not yet pre- 

 pared to present any conclusions. 



Dr. B. A. Gould made a communication on the diurnal 

 change in the position of the azimuthal arms of the transit- 

 instrument along the Atlantic coast of the United States. 



Professor Hitchcock, in this connection, recounted several 

 observations showing a singular pressure on the earth's sur- 

 face from the east, as exhibited in the pushing up of the strata 

 in a quarry at Portland, Connecticut, and at Rutland, Ver- 

 mont. And he suggested that this might account for certain 

 peculiar rumbling sounds in the earth heard at times in Con- 

 necticut. 



Professor Parsons discoursed upon the resemblances be- 

 tween the German and English Jury and the analogous insti- 

 tutions of Greece and Rome. 



Five hundred and nineteenth Meeting. 



March 10, 1863. — Monthly Meeting. 



The President in the chair. 



The Corresponding Secretary read a letter from General 

 A. A. Humphreys, dated Camp near Falmouth, Virginia, in 

 acknowledgment of the announcement of his election as an 

 Associate Fellow. 



Also, from Captain Henry L. Abbot, U. S. Engineers, in 

 acknowledgment of his election as a Fellow of the Academy. 



Dr. Charles Pickering propounded the inquiry whether the 

 irregularity in the eclipses of Jupiter's satellites may not be 

 due to the difference between real and apparent time. To 

 wdiich Professor Peirce returned a negative response. 



